An experiment was conducted to study the effects of different milking frequencies on milk and reproductive performance of Holstein dairy cows during early lactation. For this pourpose 21 multiparous Holsteins dairy cows were assigned in three treatments and 7 cows in each. Treatments were: 1) three times milking per day for 42 days after calving (3X); 2) milking six times per day for 21 days after calving and then change to three times subsequently (6X-3X); and 3) milking six times per day for 42 days after calving (6X). Average daily dry matter intake (DMI), body weight changes, average daily milk production and its composition, some blood metabolites and progesterone concentrations and also the reproductive parameters were measured every week. Results showed that the milking strategies had no significant effect on DMI. In 42 days, weight loss in treatment 6x was more than the other treatments and these differences tend to be statistically significant (P 0.1). Average milk and FCM yield were greater in 6x cows than 3x during the first and second 21 days of lactation (P 0.05). These traits also were greater in 6x cows than 3x during the total experimental period (P 0.05). However, the 6x-3x treatment had no significant difference with the other treatments. Miilk fat was affected by milking strategies. During the first 21 days of lactation and in total experimental period 6x cows had higher (P 0.05) daily milk fat yield than 3x cows. Among blood metabolites, 6x cows had higher NEFA concentration than 3x cows (P 0.05), however the other metabolites and progesterone were not significantly affected by treatments. Reproductive parameters including the number of artificial insemination per cow, days to first insemination, and open days were not affected by milking strategies. The results showed that 6 times milking per day during the first 42 days of lactation may increase milk production in Holstein dairy cows without any negative effect on reproductive parameters Keywords : milking frequency, Holstein cows, milk production, blood metabolites, reproduction
